1. Field of the Invention
This invention generally relates to a Stirling cycle engine, and more particularly, to a driving apparatus for a Stirling cycle engine.
2. Description of the Prior Art
In conventional Stirling cycle engine systems there are various kinds of actuating gas circuits having an expansion space, a compression space, a regenerator and a heat radiator. The actuating gas circuits may be comprised of just one circuit or a combination of a plurality of circuits.
The construction by one actuating gas circuit is disclosed in Japanese Patent Publication No. 47(1972)-44580. In this system, the torque change is large so that vibration, noise and durability become matters of concern. The construction by a combination of a plurality of circuits is disclosed in Japanese Patent Publication No. 51(1976)-10310. Many parts are required for this construction so that the manufacturing cost becomes high.
Further, there is the Japanese Laid-Open Patent Application No. 54(1979)-12062 in which the actuating gas circuit is constructed by two circuits in a manner similar to the present invention. A diaphragm 9 is provided on a rod 5 for preventing the oil flux in this construction as shown in FIG. 5. A crank axle 4 has three branches so that the construction becomes simple. The operating point of the load on the crank axle 4 by a piston 1 is one point, so the change of the bending moment of the crank axle 4 is little and the vibration is decreased. However, a seal member 6 is required on the rod 5 of the piston 1 in this construction. The function of the seal member 6 is important.
If the actuating gas from a compression space in an upper space 7 of the diaphragm 9 leaks, the compression ratio within the actuating gas circuit is decreased and the output force is decreased. Besides these disadvantages, the pressure in the upper space 7 of the diaphragm 9 is increased due to the presence of the seal member 6 and the pressure difference between the upper space 7 of the diaphragm 9 and the pressure within a crankcase 8 becomes large thereby adding to the possibility for leakage of the actuating gas. As a result, the diaphragm 9 comes off or is damaged and the oil 10 within the crankcase 8 rises up within the actuating gas circuit and output power is lowered. Further, as the capacity of the upper space 7 of the diaphragm 9 is changed due to the up and down movement (reciprocating movement) of the rod 5, the pressure is constantly changing and the diaphragm may come off or be damaged.
It is a possibility to provide a surge tank (not shown in FIG. 5) communicating with the upper space 7 of the diaphragm 9 for minimizing the above-mentioned drawbacks. However, in this case, the surge tank must have an extremely large capacity for sufficiently minimizing the pressure change.